[V8] UPDATE Engine Trouble (v6 - but still Audi)

[Tony and Lillie]

Correct. If you have a completely dead ECU, you will have no communication. That's quite commonly seen on later VAG procucts in both the trans computers (water in the passenger floor) and ABS modules. You get no communication and no codes.

Having said that, it is possible for one portion of the ECU to go bad. But, it's not that common. However, it did happen to my V8Q. In that case, the ECU could not see the engine coolant temp sender signal to adjust the mixture, so it started VERY poorly. I checked everything out, and in the end replaced the ECU. Problem solved.

In regards to the V6 vs VR6, there are similarities. However, the basic engine hardware is completely different. The 2.8 12V V6 in the Audi's is a conventional v-6 with seperate cylinder heads and a timing belt on the front of the engine. The 2.8 12v VR6 is a 15degree v-6 with one cylinder head bolted to the single head deck surface. It uses a timing chain, mounted at the rear of the engine, as do all the VR6 engines.------However, these engines were both produced at about the same time, and both use very similar Bosch Motronic engine control systems. So, a lot of the basic troubleshooting is the same.

As for checking the crank position sensor, pull the plug to it and ohms check it. Just like on the V8Q, two of the terminals (I think the outside) should measure about 1000 ohms. If not, it's fried. BTW, I'll agree that no spark and no fuel points in that general direction. The ECU is more than likely not seeing a signal that it needs for the engine to run, and therefore is not producing the feedback of fuel and spark. I'd be looking at the crank and cam postion sensors first, then checking the wiring to the ECU from those sensors. Also, depending on how hot the engine got (not very from the sounds of it) you may want to give it a good lookover for any melted/burned wires.

Jason, where are you located?

Tony



>Subject: [V8]  UPDATE Engine Trouble (v6 - but still Audi)
>
>I wouldn't suspect a totally dead ECU, since he was able to read codes, 
>right?
>
>>----Alkuperäinen viesti----
>>
>>Jason Wilkerson wrote:
>> > What would cause no spark and no fuel?  Thanks.
>>
>>Another guess: no spark and no fuel points to the ECU not letting 
>that happen. 
>>It could be the ECU doesn't get a signal from the CPS, and so isn't 
>letting fuel 
>>and spark happen. It could be the ECU is dead